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feat: reserve multiboot info, modules, and null page at startup

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This commit is contained in:
Katharina 2026-06-28 22:31:44 +02:00
parent bfa71d5836
commit cb33372066
1 changed files with 40 additions and 1 deletions
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41
kernel/src/init/init.cpp
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@ -34,6 +34,33 @@ static void step(const char* name, T&& fn) {
print("\n"); print("\n");
} }
template<typename Fn>
static void for_each_boot_reserved_range(Fn&& fn) {
fn(paddr_t{0}, page_size);
const multiboot::info* mb = multiboot::get_multiboot_info();
uint64_t info_phys = reinterpret_cast<uint64_t>(mb) - high_base;
fn(paddr_t{info_phys}, mb->total_size);
multiboot::visit_all(mb, [&](const multiboot::tag_module* module) {
fn(paddr_t{module->mod_start}, module->mod_end - module->mod_start);
});
}
static bool is_in_boot_reserved_range(paddr_t ptr, size_t size) {
bool res = false;
for_each_boot_reserved_range([&](paddr_t start, size_t length) {
if(length == 0) {
return;
}
if(ptr.address < start.address + length &&
start.address < ptr.address + size) {
res = true;
}
});
return res;
}
optional<paddr_t> findInitialMemoryPages(const multiboot::tag_mmap* multiboot_info, size_t count) { optional<paddr_t> findInitialMemoryPages(const multiboot::tag_mmap* multiboot_info, size_t count) {
const auto* base = reinterpret_cast<const uint8_t*>(multiboot_info->entries); const auto* base = reinterpret_cast<const uint8_t*>(multiboot_info->entries);
const auto* end = reinterpret_cast<const uint8_t*>(multiboot_info) + multiboot_info->size; const auto* end = reinterpret_cast<const uint8_t*>(multiboot_info) + multiboot_info->size;
@ -49,7 +76,8 @@ optional<paddr_t> findInitialMemoryPages(const multiboot::tag_mmap* multiboot_in
continue; continue;
} }
for(auto ptr = start_ptr; ptr < (end_ptr - page_size * (count - 1)); ptr += page_size) { for(auto ptr = start_ptr; ptr < (end_ptr - page_size * (count - 1)); ptr += page_size) {
if(!is_in_reserved_section(paddr_t{ptr}, page_size)) { if(!is_in_reserved_section(paddr_t{ptr}, page_size) &&
!is_in_boot_reserved_range(paddr_t{ptr}, page_size)) {
return paddr_t{ptr}; return paddr_t{ptr};
} }
} }
@ -98,6 +126,17 @@ void PhysicalAllocator::init(const multiboot::tag_mmap* multiboot_info) {
}); });
}); });
step("boot_reserved", [&]() {
for_each_boot_reserved_range([&](paddr_t start, size_t length){
if(length == 0) {
return;
}
auto start_ptr = start.address & ~(page_size - 1);
auto end_ptr = (start.address + length + page_size - 1) & ~(page_size - 1);
alloc.force({paddr_t{start_ptr}, (end_ptr - start_ptr) / page_size}, false);
});
});
alloc.force({page, 1}, false); alloc.force({page, 1}, false);
PhysicalAllocator::getInstance() = alloc; PhysicalAllocator::getInstance() = alloc;